package com.xiyuan.smartutils.client.ws.util;

import java.util.Arrays;

/**
 * A very fast and memory efficient class to encode and decode to and from
 * BASE64 in full accordance with RFC 2045.<br>
 * <br>
 * On Windows XP sp1 with 1.4.2_04 and later ;), this encoder and decoder is
 * about 10 times faster on small arrays (10 - 1000 bytes) and 2-3 times as fast
 * on larger arrays (10000 - 1000000 bytes) compared to
 * <code>sun.misc.Encoder()/Decoder()</code>.<br>
 * <br>
 * <p>
 * On byte arrays the encoder is about 20% faster than Jakarta Commons Base64
 * Codec for encode and about 50% faster for decoding large arrays. This
 * implementation is about twice as fast on very small arrays (&lt 30 bytes). If
 * source/destination is a <code>String</code> this version is about three times
 * as fast due to the fact that the Commons Codec result has to be recoded to a
 * <code>String</code> from <code>byte[]</code>, which is very expensive.<br>
 * <br>
 * <p>
 * This encode/decode algorithm doesn't create any temporary arrays as many
 * other codecs do, it only allocates the resulting array. This produces less
 * garbage and it is possible to handle arrays twice as large as algorithms that
 * create a temporary array. (E.g. Jakarta Commons Codec). It is unknown whether
 * Sun's <code>sun.misc.Encoder()/Decoder()</code> produce temporary arrays but
 * since performance is quite low it probably does.<br>
 * <br>
 * <p>
 * The encoder produces the same output as the Sun one except that the Sun's
 * encoder appends a trailing line separator if the last character isn't a pad.
 * Unclear why but it only adds to the length and is probably a side effect.
 * Both are in conformance with RFC 2045 though.<br>
 * Commons codec seem to always att a trailing line separator.<br>
 * <br>
 *
 * <b>Note!</b> The encode/decode method pairs (types) come in three versions
 * with the <b>exact</b> same algorithm and thus a lot of code redundancy. This
 * is to not create any temporary arrays for transcoding to/from different
 * format types. The methods not used can simply be commented out.<br>
 * <br>
 * <p>
 * There is also a "fast" version of all decode methods that works the same way
 * as the normal ones, but har a few demands on the decoded input. Normally
 * though, these fast verions should be used if the source if the input is known
 * and it hasn't bee tampered with.<br>
 * <br>
 * <p>
 * If you find the code useful or you find a bug, please send me a note at
 * base64 @ miginfocom . com.
 * <p>
 * Licence (BSD): ==============
 * <p>
 * Copyright (c) 2004, Mikael Grev, MiG InfoCom AB. (base64 @ miginfocom . com)
 * All rights reserved.
 * <p>
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer. Redistributions in binary
 * form must reproduce the above copyright notice, this list of conditions and
 * the following disclaimer in the documentation and/or other materials provided
 * with the distribution. Neither the name of the MiG InfoCom AB nor the names
 * of its contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * <p>
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * @author xiyuan Date: 2004-aug-02 Time: 11:31:11
 * @version 2.2
 */

public class Base64 {
    private static final char[] CA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
    private static final int[] IA = new int[256];
    
    static {
        Arrays.fill(IA, -1);
        for (int i = 0, iS = CA.length; i < iS; i++) {IA[CA[i]] = i;}
        
        IA['='] = 0;
    }
    
    // ****************************************************************************************
    // * char[] version
    // ****************************************************************************************
    
    /**
     * Encodes a raw byte array into a BASE64 <code>char[]</code> representation
     * i accordance with RFC 2045.
     *
     * @param sArr    The bytes to convert. If <code>null</code> or length 0 an
     *                empty array will be returned.
     * @param lineSep Optional "\r\n" after 76 characters, unless end of
     *                file.<br>
     *                No line separator will be in breach of RFC 2045 which
     *                specifies max 76 per line but will be a little faster.
     * @return A BASE64 encoded array. Never <code>null</code>.
     */
    public static final char[] encodeToChar(byte[] sArr, boolean lineSep) {
        // Check special case
        int sLen = sArr != null ? sArr.length : 0;
        if (sLen == 0) {return new char[0];}
        
        int eLen = (sLen / 3) * 3; // Length of even 24-bits.
        int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count
        int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of
        // returned
        // array
        char[] dArr = new char[dLen];
        
        // Encode even 24-bits
        for (int s = 0, d = 0, cc = 0; s < eLen; ) {
            // Copy next three bytes into lower 24 bits of int, paying attension
            // to sign.
            int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);
            
            // Encode the int into four chars
            dArr[d++] = CA[(i >>> 18) & 0x3f];
            dArr[d++] = CA[(i >>> 12) & 0x3f];
            dArr[d++] = CA[(i >>> 6) & 0x3f];
            dArr[d++] = CA[i & 0x3f];
            
            // Add optional line separator
            if (lineSep && ++cc == 19 && d < dLen - 2) {
                dArr[d++] = '\r';
                dArr[d++] = '\n';
                cc = 0;
            }
        }
        
        // Pad and encode last bits if source isn't even 24 bits.
        int left = sLen - eLen; // 0 - 2.
        if (left > 0) {
            // Prepare the int
            int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);
            
            // Set last four chars
            dArr[dLen - 4] = CA[i >> 12];
            dArr[dLen - 3] = CA[(i >>> 6) & 0x3f];
            dArr[dLen - 2] = left == 2 ? CA[i & 0x3f] : '=';
            dArr[dLen - 1] = '=';
        }
        return dArr;
    }
    
    /**
     * Decodes a BASE64 encoded char array. All illegal characters will be
     * ignored and can handle both arrays with and without line separators.
     *
     * @param sArr The source array. <code>null</code> or length 0 will return
     *             an empty array.
     * @return The decoded array of bytes. May be of length 0. Will be
     * <code>null</code> if the legal characters (including '=') isn't
     * divideable by 4. (I.e. definitely corrupted).
     */
    public static final byte[] decode(char[] sArr) {
        // Check special case
        int sLen = sArr != null ? sArr.length : 0;
        if (sLen == 0) {return new byte[0];}
        
        // Count illegal characters (including '\r', '\n') to know what size the
        // returned array will be,
        // so we don't have to reallocate & copy it later.
        int sepCnt = 0; // Number of separator characters. (Actually illegal
        // characters, but that's a bonus...)
        for (int i = 0; i < sLen; i++) // If input is "pure" (I.e. no line
        // separators or illegal chars) base64
        // this loop can be commented out.
        {if (IA[sArr[i]] < 0) {sepCnt++;}}
        
        // Check so that legal chars (including '=') are evenly divideable by 4
        // as specified in RFC 2045.
        if ((sLen - sepCnt) % 4 != 0) {return null;}
        
        int pad = 0;
        for (int i = sLen; i > 1 && IA[sArr[--i]] <= 0; ) {if (sArr[i] == '=') {pad++;}}
        
        int len = ((sLen - sepCnt) * 6 >> 3) - pad;
        
        byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
        
        for (int s = 0, d = 0; d < len; ) {
            // Assemble three bytes into an int from four "valid" characters.
            int i = 0;
            for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
                int c = IA[sArr[s++]];
                if (c >= 0) {i |= c << (18 - j * 6);}
                else {j--;}
            }
            // Add the bytes
            dArr[d++] = (byte) (i >> 16);
            if (d < len) {
                dArr[d++] = (byte) (i >> 8);
                if (d < len) {dArr[d++] = (byte) i;}
            }
        }
        return dArr;
    }
    
    /**
     * Decodes a BASE64 encoded char array that is known to be resonably well
     * formatted. The method is about twice as fast as {@link #decode(char[])}.
     * The preconditions are:<br>
     * + The array must have a line length of 76 chars OR no line separators at
     * all (one line).<br>
     * + Line separator must be "\r\n", as specified in RFC 2045 + The array
     * must not contain illegal characters within the encoded string<br>
     * + The array CAN have illegal characters at the beginning and end, those
     * will be dealt with appropriately.<br>
     *
     * @param sArr The source array. Length 0 will return an empty array.
     *             <code>null</code> will throw an exception.
     * @return The decoded array of bytes. May be of length 0.
     */
    public static final byte[] decodeFast(char[] sArr) {
        // Check special case
        int sLen = sArr.length;
        if (sLen == 0) {return new byte[0];}
        
        int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.
        
        // Trim illegal chars from start
        while (sIx < eIx && IA[sArr[sIx]] < 0) {sIx++;}
        
        // Trim illegal chars from end
        while (eIx > 0 && IA[sArr[eIx]] < 0) {eIx--;}
        
        // get the padding count (=) (0, 1 or 2)
        int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count
        // '='
        // at
        // end.
        int cCnt = eIx - sIx + 1; // Content count including possible separators
        int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;
        
        int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded
        // bytes
        byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
        
        // Decode all but the last 0 - 2 bytes.
        int d = 0;
        for (int cc = 0, eLen = (len / 3) * 3; d < eLen; ) {
            // Assemble three bytes into an int from four "valid" characters.
            int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];
            
            // Add the bytes
            dArr[d++] = (byte) (i >> 16);
            dArr[d++] = (byte) (i >> 8);
            dArr[d++] = (byte) i;
            
            // If line separator, jump over it.
            if (sepCnt > 0 && ++cc == 19) {
                sIx += 2;
                cc = 0;
            }
        }
        
        if (d < len) {
            // Decode last 1-3 bytes (incl '=') into 1-3 bytes
            int i = 0;
            for (int j = 0; sIx <= eIx - pad; j++) {i |= IA[sArr[sIx++]] << (18 - j * 6);}
            
            for (int r = 16; d < len; r -= 8) {dArr[d++] = (byte) (i >> r);}
        }
        
        return dArr;
    }
    
    // ****************************************************************************************
    // * byte[] version
    // ****************************************************************************************
    
    /**
     * Encodes a raw byte array into a BASE64 <code>byte[]</code> representation
     * i accordance with RFC 2045.
     *
     * @param sArr    The bytes to convert. If <code>null</code> or length 0 an
     *                empty array will be returned.
     * @param lineSep Optional "\r\n" after 76 characters, unless end of
     *                file.<br>
     *                No line separator will be in breach of RFC 2045 which
     *                specifies max 76 per line but will be a little faster.
     * @return A BASE64 encoded array. Never <code>null</code>.
     */
    public static final byte[] encodeToByte(byte[] sArr, boolean lineSep) {
        // Check special case
        int sLen = sArr != null ? sArr.length : 0;
        if (sLen == 0) {return new byte[0];}
        
        int eLen = (sLen / 3) * 3; // Length of even 24-bits.
        int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count
        int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of
        // returned
        // array
        byte[] dArr = new byte[dLen];
        
        // Encode even 24-bits
        for (int s = 0, d = 0, cc = 0; s < eLen; ) {
            // Copy next three bytes into lower 24 bits of int, paying attension
            // to sign.
            int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);
            
            // Encode the int into four chars
            dArr[d++] = (byte) CA[(i >>> 18) & 0x3f];
            dArr[d++] = (byte) CA[(i >>> 12) & 0x3f];
            dArr[d++] = (byte) CA[(i >>> 6) & 0x3f];
            dArr[d++] = (byte) CA[i & 0x3f];
            
            // Add optional line separator
            if (lineSep && ++cc == 19 && d < dLen - 2) {
                dArr[d++] = '\r';
                dArr[d++] = '\n';
                cc = 0;
            }
        }
        
        // Pad and encode last bits if source isn't an even 24 bits.
        int left = sLen - eLen; // 0 - 2.
        if (left > 0) {
            // Prepare the int
            int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);
            
            // Set last four chars
            dArr[dLen - 4] = (byte) CA[i >> 12];
            dArr[dLen - 3] = (byte) CA[(i >>> 6) & 0x3f];
            dArr[dLen - 2] = left == 2 ? (byte) CA[i & 0x3f] : (byte) '=';
            dArr[dLen - 1] = '=';
        }
        return dArr;
    }
    
    /**
     * Decodes a BASE64 encoded byte array. All illegal characters will be
     * ignored and can handle both arrays with and without line separators.
     *
     * @param sArr The source array. Length 0 will return an empty array.
     *             <code>null</code> will throw an exception.
     * @return The decoded array of bytes. May be of length 0. Will be
     * <code>null</code> if the legal characters (including '=') isn't
     * divideable by 4. (I.e. definitely corrupted).
     */
    public static final byte[] decode(byte[] sArr) {
        // Check special case
        int sLen = sArr.length;
        
        // Count illegal characters (including '\r', '\n') to know what size the
        // returned array will be,
        // so we don't have to reallocate & copy it later.
        int sepCnt = 0; // Number of separator characters. (Actually illegal
        // characters, but that's a bonus...)
        for (int i = 0; i < sLen; i++) // If input is "pure" (I.e. no line
        // separators or illegal chars) base64
        // this loop can be commented out.
        {if (IA[sArr[i] & 0xff] < 0) {sepCnt++;}}
        
        // Check so that legal chars (including '=') are evenly divideable by 4
        // as specified in RFC 2045.
        if ((sLen - sepCnt) % 4 != 0) {return null;}
        
        int pad = 0;
        for (int i = sLen; i > 1 && IA[sArr[--i] & 0xff] <= 0; ) {if (sArr[i] == '=') {pad++;}}
        
        int len = ((sLen - sepCnt) * 6 >> 3) - pad;
        
        byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
        
        for (int s = 0, d = 0; d < len; ) {
            // Assemble three bytes into an int from four "valid" characters.
            int i = 0;
            for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
                int c = IA[sArr[s++] & 0xff];
                if (c >= 0) {i |= c << (18 - j * 6);}
                else {j--;}
            }
            
            // Add the bytes
            dArr[d++] = (byte) (i >> 16);
            if (d < len) {
                dArr[d++] = (byte) (i >> 8);
                if (d < len) {dArr[d++] = (byte) i;}
            }
        }
        
        return dArr;
    }
    
    /**
     * Decodes a BASE64 encoded byte array that is known to be resonably well
     * formatted. The method is about twice as fast as {@link #decode(byte[])}.
     * The preconditions are:<br>
     * + The array must have a line length of 76 chars OR no line separators at
     * all (one line).<br>
     * + Line separator must be "\r\n", as specified in RFC 2045 + The array
     * must not contain illegal characters within the encoded string<br>
     * + The array CAN have illegal characters at the beginning and end, those
     * will be dealt with appropriately.<br>
     *
     * @param sArr The source array. Length 0 will return an empty array.
     *             <code>null</code> will throw an exception.
     * @return The decoded array of bytes. May be of length 0.
     */
    public static final byte[] decodeFast(byte[] sArr) {
        // Check special case
        int sLen = sArr.length;
        if (sLen == 0) {return new byte[0];}
        
        int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.
        
        // Trim illegal chars from start
        while (sIx < eIx && IA[sArr[sIx] & 0xff] < 0) {sIx++;}
        
        // Trim illegal chars from end
        while (eIx > 0 && IA[sArr[eIx] & 0xff] < 0) {eIx--;}
        
        // get the padding count (=) (0, 1 or 2)
        int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count
        // '='
        // at
        // end.
        int cCnt = eIx - sIx + 1; // Content count including possible separators
        int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;
        
        int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded
        // bytes
        byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
        
        // Decode all but the last 0 - 2 bytes.
        int d = 0;
        for (int cc = 0, eLen = (len / 3) * 3; d < eLen; ) {
            // Assemble three bytes into an int from four "valid" characters.
            int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];
            
            // Add the bytes
            dArr[d++] = (byte) (i >> 16);
            dArr[d++] = (byte) (i >> 8);
            dArr[d++] = (byte) i;
            
            // If line separator, jump over it.
            if (sepCnt > 0 && ++cc == 19) {
                sIx += 2;
                cc = 0;
            }
        }
        
        if (d < len) {
            // Decode last 1-3 bytes (incl '=') into 1-3 bytes
            int i = 0;
            for (int j = 0; sIx <= eIx - pad; j++) {i |= IA[sArr[sIx++]] << (18 - j * 6);}
            
            for (int r = 16; d < len; r -= 8) {dArr[d++] = (byte) (i >> r);}
        }
        
        return dArr;
    }
    
    // ****************************************************************************************
    // * String version
    // ****************************************************************************************
    
    /**
     * Encodes a raw byte array into a BASE64 <code>String</code> representation
     * i accordance with RFC 2045.
     *
     * @param sArr    The bytes to convert. If <code>null</code> or length 0 an
     *                empty array will be returned.
     * @param lineSep Optional "\r\n" after 76 characters, unless end of
     *                file.<br>
     *                No line separator will be in breach of RFC 2045 which
     *                specifies max 76 per line but will be a little faster.
     * @return A BASE64 encoded array. Never <code>null</code>.
     */
    public static final String encodeToString(byte[] sArr, boolean lineSep) {
        // Reuse char[] since we can't create a String incrementally anyway and
        // StringBuffer/Builder would be slower.
        return new String(encodeToChar(sArr, lineSep));
    }
    
    /**
     * Decodes a BASE64 encoded <code>String</code>. All illegal characters will
     * be ignored and can handle both strings with and without line
     * separators.<br>
     * <b>Note!</b> It can be up to about 2x the speed to call
     * <code>decode(str.toCharArray())</code> instead. That will create a
     * temporary array though. This version will use <code>str.charAt(i)</code>
     * to iterate the string.
     *
     * @param str The source string. <code>null</code> or length 0 will return
     *            an empty array.
     * @return The decoded array of bytes. May be of length 0. Will be
     * <code>null</code> if the legal characters (including '=') isn't
     * divideable by 4. (I.e. definitely corrupted).
     */
    public static final byte[] decode(String str) {
        // Check special case
        int sLen = str != null ? str.length() : 0;
        if (sLen == 0) {return new byte[0];}
        
        // Count illegal characters (including '\r', '\n') to know what size the
        // returned array will be,
        // so we don't have to reallocate & copy it later.
        int sepCnt = 0; // Number of separator characters. (Actually illegal
        // characters, but that's a bonus...)
        for (int i = 0; i < sLen; i++) // If input is "pure" (I.e. no line
        // separators or illegal chars) base64
        // this loop can be commented out.
        {if (IA[str.charAt(i)] < 0) {sepCnt++;}}
        
        // Check so that legal chars (including '=') are evenly divideable by 4
        // as specified in RFC 2045.
        if ((sLen - sepCnt) % 4 != 0) {return null;}
        
        // Count '=' at end
        int pad = 0;
        for (int i = sLen; i > 1 && IA[str.charAt(--i)] <= 0; ) {if (str.charAt(i) == '=') {pad++;}}
        
        int len = ((sLen - sepCnt) * 6 >> 3) - pad;
        
        byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
        
        for (int s = 0, d = 0; d < len; ) {
            // Assemble three bytes into an int from four "valid" characters.
            int i = 0;
            for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
                int c = IA[str.charAt(s++)];
                if (c >= 0) {i |= c << (18 - j * 6);}
                else {j--;}
            }
            // Add the bytes
            dArr[d++] = (byte) (i >> 16);
            if (d < len) {
                dArr[d++] = (byte) (i >> 8);
                if (d < len) {dArr[d++] = (byte) i;}
            }
        }
        return dArr;
    }
    
    /**
     * Decodes a BASE64 encoded string that is known to be resonably well
     * formatted. The method is about twice as fast as {@link #decode(String)}.
     * The preconditions are:<br>
     * + The array must have a line length of 76 chars OR no line separators at
     * all (one line).<br>
     * + Line separator must be "\r\n", as specified in RFC 2045 + The array
     * must not contain illegal characters within the encoded string<br>
     * + The array CAN have illegal characters at the beginning and end, those
     * will be dealt with appropriately.<br>
     *
     * @param s The source string. Length 0 will return an empty array.
     *          <code>null</code> will throw an exception.
     * @return The decoded array of bytes. May be of length 0.
     */
    public static final byte[] decodeFast(String s) {
        // Check special case
        int sLen = s.length();
        if (sLen == 0) {return new byte[0];}
        
        int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.
        
        // Trim illegal chars from start
        while (sIx < eIx && IA[s.charAt(sIx) & 0xff] < 0) {sIx++;}
        
        // Trim illegal chars from end
        while (eIx > 0 && IA[s.charAt(eIx) & 0xff] < 0) {eIx--;}
        
        // get the padding count (=) (0, 1 or 2)
        int pad = s.charAt(eIx) == '=' ? (s.charAt(eIx - 1) == '=' ? 2 : 1) : 0; // Count
        // '='
        // at
        // end.
        int cCnt = eIx - sIx + 1; // Content count including possible separators
        int sepCnt = sLen > 76 ? (s.charAt(76) == '\r' ? cCnt / 78 : 0) << 1 : 0;
        
        int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded
        // bytes
        byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
        
        // Decode all but the last 0 - 2 bytes.
        int d = 0;
        for (int cc = 0, eLen = (len / 3) * 3; d < eLen; ) {
            // Assemble three bytes into an int from four "valid" characters.
            int i = IA[s.charAt(sIx++)] << 18 | IA[s.charAt(sIx++)] << 12 | IA[s.charAt(sIx++)] << 6 | IA[s.charAt(sIx++)];
            
            // Add the bytes
            dArr[d++] = (byte) (i >> 16);
            dArr[d++] = (byte) (i >> 8);
            dArr[d++] = (byte) i;
            
            // If line separator, jump over it.
            if (sepCnt > 0 && ++cc == 19) {
                sIx += 2;
                cc = 0;
            }
        }
        
        if (d < len) {
            // Decode last 1-3 bytes (incl '=') into 1-3 bytes
            int i = 0;
            for (int j = 0; sIx <= eIx - pad; j++) {i |= IA[s.charAt(sIx++)] << (18 - j * 6);}
            
            for (int r = 16; d < len; r -= 8) {dArr[d++] = (byte) (i >> r);}
        }
        
        return dArr;
    }
}
